For packaging, storage, and transportation of bulk goods, box packages or other packages of rigid construction are used, which are placed on a base (usually a pallet). The box packages consist of boxes of corrugated board. The box of corrugated board is, as a rule, provided with an inner sack into which the bulk goods are placed. When filled with the bulk goods, such a package has a quadrangular shape, i.e., the shape of the paperboard box, and thus utilizes the transportation base maximally, even though the package as such is expensive.
Unit-load sacks are also used for packaging, storage, and transportation of bulk goods. A unit-load sack is less expensive than a box package, but its drawback is its round shape when filled, whereby it utilizes the transportation base less efficiently than a box package does. It is understood in the art that bulk goods do not have a specific shape in bulk, such as grains, fertilizers and other granular materials. Thus, unit-load sacks bulge when filled and do not retain any definite shape.
In prior art related to the invention, U.S. Pat. No. 3,670,880 (Burleson et al.) shows an arrangement wherein paperboard receptacles are filled with flexible products and then a stack of the paperboard receptacles is surrounded by a heat-shrinkable plastic outer covering. The paperboard receptacle is made of a multilayer corrugated board and protects the flexible products from moisture.
U.S. Pat. No. 5,005,335 (Yourgalite et al.) shows a stretch wrapping operation wherein there are two layers that are tightly wrapped around the articles through a banding process.
U.S. Pat. No. 4,968,951 (Everman et al.) shows a method in which an inner sack is formed from a reel of inner sack blanks, placed inside a paperboard box, filled when it is in the paperboard box and the both the inner sack and the paper board box are closed. By retaining the inner sack in the rigid paperboard box, the inner sack does not bulge upon its filling with the bulk goods.